Abstract Body

The perceptual separation of tactile stimuli presented in quick succession into temporally distinct sensations is linked to low-frequency prestimulus neural oscillations. Hepatic encephalopathy (HE) is a clinical complication in patients with liver cirrhosis, featuring prominent visual and tactile perceptual deficits. Here, we investigated if the relationship between tactile temporal resolution and low-frequency prestimulus neural oscillations is likewise present in HE patients demonstrating tactile perceptual impairments.

17 controls (12 male, 63 ± 2.8 y) and 17 HE patients (13 male, 59 ± 2.3 y) performed a tactile temporal discrimination task. Two suprathreshold electrical stimuli with varying stimulus-onset-asynchrony (SOA; 0-400 ms) were presented to the left index finger. Participants reported if they perceived the stimulation as one single or two temporally separate sensations, yielding an individual measure of tactile temporal resolution. Whole-head neuromagnetic activity recorded during the task was used to compute source-level peak frequency estimates in the low frequency range (5-30 Hz), which were compared across groups and correlated with metrics of tactile temporal resolution.

HE patients perceived a single stimulus more often than controls for SOAs between 125-400 ms, indicating impaired tactile temporal resolution. Patients demonstrated lower alpha- and beta- band peak frequencies in posterior and frontal cortex areas, respectively. Across groups, peak frequencies were negatively correlated with metrics of individual tactile temporal resolution.

Perceptual impairments in HE extend to the tactile domain. Established oscillatory parameters known to underlie temporal perception in healthy subjects are decreased in HE patients and remain connected to metrics of impaired tactile temporal sampling.